The measurement and analysis of the spectrum of the V <- N transition of 2,3-dideuterobutadiene has lead to the reinterpretation of the vibrational substructure of this transition. The diffuse subbands observed were shown to arise from transitions to mixed normal modes of the excited state, not to transitions to a progression in the C=C stretching vibration of the molecule. The diffuseness of the transition was shown to be due to rapid nonradiative relaxation through or over a very small barrier in the C=C torsion to a almost degenerate electronic state. Through an investigation of the spectral emission of tetramethyl butadiene, the energy ordering of the two states in question was shown to be in inverted in TMB from that observed in butadiene. The probably analogue of the acceptor state in butadiene was observed for the first time in any diene in the essentially cis isomer, cyclopentadiene. A polarization-selected resonant multiphoton ionization spectroscopic investigation of acetone was conducted to resolve existing questions concerning the excited state energy ordering in that molecule.